Daboll's Schoolmaster's Assistant: Improved and Enlarged; Being a Plain ...

ANOTHER METHOD. Write down the given principal in cents, which multiply by the rate, and divide by 100 as before, and you will have the interest for a year, in cents, and decimals of a cent, as follows:

9. What is the interest of $73, 65 Gents for a year, at 6 per cent. ?

| Principal 7365 cents.

Ans. 441,90cts.=441%ets. or $4, 41cts. 97. 11.10. Required the interest of $85, 45cts. for a year, at 7 per cent. ? " Cents.

Principal 8545

Ans. 598, 15 cents,=$5,98cts. 13m.

.: CASE II. To find the simple interest of any sum of money, for any

number of years, and parts of a year.

GENERAL RULE.

Ist. Find the interest of the given sum for one year.

2d. Multiply the interest of one year by the given pumber of years, and the product will be the answer for that time.

Sd. If there be parts of a year, as " months and days, work for the months by the aliquot parts of a year, and for the days by the Rule of Three Direct, or by allowing 30 days to the month, and taking aliquot pårts of the same. *

* By allowing the month to be 30 days, and taking aliquot parts thereof, you will have the interest of any ordinary gum sufficiently exact for common use; but if the sum be very large, you may say,

Ås 365 days : is to the interest of one year : : so is the miren number of days : to the interest reruired.

EXAMPLES. 1. What is the interest of 751. 8s. 4d. for 5 years and 2 months, at 6l. per cent, per annum ?

20

75 8 4 1

f. S. d. 6 2mo.=:54 10 6 Interest for 1 year. 4/52 10 0

22 12 6 do. for 5 years."

0 15 1 do. for 2 months. * 10/50

£23 7 7 Ans. 6100

... : 2. What is the interest of 64 dollars 58 cents, for years, 5 months, and ten days at 5 per cent. ?

$ 64,58

| 322,90 Interest for 1 year in cents, per

9. Of 1 dollar for 12 years at 5 per cent. ?

Ans. 60cts. 10. Of 215 dollars 34 cts. for 4 and a half years, at 3 and a half per cent. ? . Ans. $33, 9icts. 6m.

11. What is the amount of 324 dollars, 61 cents, for 5 years and 5 months, at 6 per cent. ?

Ans. $430, 10cts. 8.467m. 12. What will 50001. amount to in 12 years and 10 months, at 6 per cent. ?

Ans. £,5310. 13. What is the interest of 2571. 5s. 1d. for 1 year and 3 quarters, at 4 per cento? Ins. £18 Os. 1d. 3qrs.

14. What is the interest of 279 dollars, 87 cents for % years and a half, at.7 per cent. per annum?

Ans. $48, 97cts. 74m. 15. What will 2791. 13s. 8d, amount to in 3 years and a half at 54 per cent. .per annum ?

Ans. 6331 is, 6d. 16. What is the amount of 341 dols. 60 cts. for 5 years and 3 quarters, at 7 and a half per cent. per annum ?

Ans. $488, 91 fets. 17. What will 730 dols. amount to at 6 per cent. in 5 years, 7 months and 12 days, or of a year ?

Ans. 6975, 99cts. 18. What is the interest of 1825l. at 5 per cent. per annum, from March 4th, 1796, to March 29th, 1799, (allowing the year to contain 365 days ?). Ans. £280.

Note. The Rules for Simple Interest serve also to calculate Commission, Brokerage, Insurance, or any thing else estimated at a rate per cent.

COMMISSION, IS an allowance of so nluch per cent. to a factor or Cor respondent abroad, for buying and selling goods for his employer.

EXAMPLES 1. What will the commission of 8431 10s. come to at 5 per cent. ?

:.. BROKERAGE, IS an allowance of so much per cent. to persons assiste ing merchants, or factors, in purchasing or selling goods.

EXAMPLES. 1. What is the brokerage of 7501. 85. 4d. at 68. 8d. per cent. ?

Here I first find the brokerage at 1

pound per cent. and then for the given rate, which is of a pound.

s. d. £. s. d. grs. 6-8=*) 10 1*..

Ans. £2 10 0 11

20

10,08

12

1,00 2. What is the brokerage upon 4125 dols. at or 75 cents per cent. ?

Ans. $30, 93cts, 71m. 3. If a broker sells goods to the amount of 5000 dols. what is his demand at 65 cts. per cent. ?

Ans. $32, 50cts.

4. What may a broker demand, when he sells goods to the value of 508l. 175. 10d. and I allow him 15 per cent ?

Nils. £7 12s. 8d.

INSURANCE, IS a premium at so much per cent. allowed to persons and ofiices, for making good the loss of ships, houses, merchandize, &c. which may happen from storms, fire, &c. ,

EXAMPLES. 1. What is the insurance of 7251. 8s. 10d. at 124 per cent.?

in Ans. 690 13s. 71d. 2. What is the insurance of an East-India ship and cargo, valued at 123425 dollars, at 15$ per cent. ?

Ans. $19130, 87cts. 5m. S. A man's house estimated at 3500 dollars, was insu. red against fire, for 14 per cent. a year: what insurance did lie annually pay? : ins, $61, 25cts,

SHORT PRACTICAL RULES, Por calculating Interest at 6 per cent, either for montiisi.

09 months and days. I. FOR STERLING MONEY.

RULE. If the principal consists of pounds only, cut off the unit figure, and as it then stands it will be the interest for one month, in shillings and decimal parts...

2. If the principal consists of pounds, shillings, &c. reduce it to its decimal value; then remove the clecimal point one place, or figure, further towards the left hand, and as the decimal then stands, it will shew the interest for one month, in shillings, and decimals of a shilling.

EXAMPLES. 1. Required the interest of 541. for seven months and en days, at 6 per cent